We hypothesize that the screening tests in this study have the capacity to reduce mortality rates from four common adult cancers. The primary aims are to determine if certain tests and exams will prevent death from these four cancers. Flexible sigmoidoscopy will screen for colon and rectal cancer. Chest xrays will screen for lung cancer. PSA blood testing and digital rectal exam will screen for prostate cancer, and CA-125 blood testing, ultrasound and pelvic exams will screen for ovarian cancer.